I build boats with a Quattro 8000VA, a Cerbo GX and a 24V Batterie Bank with A BMV712 Shunt.
When I take take from the Quattro more than 1000W on the AC side, on the Cerbo GX screen is written, that the DC side gets negative, like the batteries will be charged (see picture) what is not the case.
The shunt is connected right. If I unplug the Patchcable from the Inverter to the Cerbo GX, the system behaves completely normal. So it is a ‘Software issue’ or a setting issue in my opinion.
In the System Setup Menu is a new Option called “Position of AC loads” this menu point I have not on my other boats! All are running the latest Cerbo GX Firmware. This is the first boat where I see this setting. I tested both settings “AC Output only” and “AC Input and Output” but nothing helped.
Have you got a separate shunt measuring DC loads or only a battery shunt?
Without a dedicated DC load shunt the system is calculating what it thinks is the difference for DC loads, so isn’t necessarily accurate.
I can enable it on mine (zero DC loads) and it produces wonderful numbers that vary in size and direction of flow.
guystewart
(Guy Stewart (Victron Community Manager))
3
To expand on Nick’s post, the DC Power box is a calculated value that shows the remainder of ‘unidentified’ power.
In this case the BMV is reporting 765W, the load is 1049W, so the difference is just assumed by the system to be coming from the DC power somewhere.
Sometimes this is accurate and useful, but in many cases it isn’t. In systems that don’t actually have a DC system element (such as DC to DC chargers without communications, or DC loads without an additional dedicated shunt) then disabling the “Has DC system” setting will just discard these differential figures rather than displaying them.
I have one Shunt on between the Batteries and the DC side, at this DC Side the Victron Quattro is connected. Wenn enabling in the Cerbo GX Settings “Has DC Settings” in the past everything was perfect.
Now at my current setting, if the Inverter consumes 3000W and the DC consumes 500W, then at the Cerbo GX is written, that the batteries will be charged with 2500W, but this is of cause wrong.
Again, if I unplug the Inverter Patchcable, everything is fine. The Shunt is installed right, so there must a a setting that needs to be changed.
@guystewart The system works more or less accurate in the past (+30 systems complete identical, all are working good) only now there is a mistake.
Yes I am sure.
It is a wrong setting, on no other Cerbo GX I have the setting “Position of AC Loads” this is new, I think this is the reason for the issue.
